Gabriele Cosmo
183 lines
8.2 KiB
C++
183 lines
8.2 KiB
C++
//
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// ********************************************************************
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// * License and Disclaimer *
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// * *
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// * The Geant4 software is copyright of the Copyright Holders of *
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// * the Geant4 Collaboration. It is provided under the terms and *
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// * conditions of the Geant4 Software License, included in the file *
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// * LICENSE and available at http://cern.ch/geant4/license . These *
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// * include a list of copyright holders. *
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// * *
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// * Neither the authors of this software system, nor their employing *
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// * institutes,nor the agencies providing financial support for this *
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// * work make any representation or warranty, express or implied, *
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// * regarding this software system or assume any liability for its *
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// * use. Please see the license in the file LICENSE and URL above *
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// * for the full disclaimer and the limitation of liability. *
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// * *
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// * This code implementation is the result of the scientific and *
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// * technical work of the GEANT4 collaboration. *
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// * By using, copying, modifying or distributing the software (or *
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// * any work based on the software) you agree to acknowledge its *
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// * use in resulting scientific publications, and indicate your *
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// * acceptance of all terms of the Geant4 Software license. *
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// ********************************************************************
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//
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// $Id: G4GoudsmitSaundersonTable.hh 93663 2015-10-28 09:50:49Z gcosmo $
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//
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// -----------------------------------------------------------------------------
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//
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// GEANT4 Class header file
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//
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// File name: G4GoudsmitSaundersonTable
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//
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// Author: Mihaly Novak / (Omrane Kadri)
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//
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// Creation date: 20.02.2009
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//
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// Class description:
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// Class to handle multiple scattering angular distributions precomputed by
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// using Kawrakow-Bielajew Goudsmit-Saunderson MSC model based on the screened
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// Rutherford DCS for elastic scattering of electrons/positrons [1,2]. This
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// class is used by G4GoudsmitSaundersonMscModel to sample the angular
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// deflection of electrons/positrons after travelling a given path.
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//
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// Modifications:
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// 04.03.2009 V.Ivanchenko cleanup and format according to Geant4 EM style
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// 18.05.2015 M. Novak This class has been completely replaced (only the original
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// class name was kept; class description was also inserted):
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// A new version of Kawrakow-Bielajew Goudsmit-Saunderson MSC model
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// based on the screened Rutherford DCS for elastic scattering of
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// electrons/positrons has been introduced[1,2]. The corresponding MSC
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// angular distributions over a 2D parameter grid have been recomputed
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// and the CDFs are now stored in a variable transformed (smooth) form
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// together with the corresponding rational interpolation parameters.
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// The new version is several times faster, more robust and accurate
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// compared to the earlier version (G4GoudsmitSaundersonMscModel class
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// that use these data has been also completely replaced)
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//
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// References:
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// [1] A.F.Bielajew, NIMB, 111 (1996) 195-208
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// [2] I.Kawrakow, A.F.Bielajew, NIMB 134(1998) 325-336
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//
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// -----------------------------------------------------------------------------
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#ifndef G4GoudsmitSaundersonTable_h
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#define G4GoudsmitSaundersonTable_h 1
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#include <vector>
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#include "G4Types.hh"
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class G4GoudsmitSaundersonTable
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{
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public:
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G4GoudsmitSaundersonTable(){};
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~G4GoudsmitSaundersonTable();
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// initialie:
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// - loads the precomputed MSC angular CDFs into memory
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// - init. material dependent MSC parameters (Moliere's screening)
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// (- only Master thread and only once)
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void Initialise();
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// samples cos(theta) i.e. angular deflection from the precomputed angular
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// distributions in the real multiple scattering case
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G4double SampleCosTheta(G4double, G4double, G4double, G4double, G4double, G4double);
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G4double SampleCosThetaII(G4double, G4double, G4double, G4double, G4double, G4double);
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// returns with the screening parameter value that results with the first
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// transport coefficient (G1) received as input parameter according to the
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// screened Rutherford DCS. Used only when fgIsUsePWATotalXsecData is TRUE
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// in G4GoudsmitSaundersonMscModel i.e. when PWA screeing is used instead of
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// Moliere's one.
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G4double GetScreeningParam(G4double);
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// samples angular deflection cos(theta) and sin(theta) for electrons/positrons
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// involving sampling of no scattering, single scattering, "few" scattering and
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// real multiple scattering
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void Sampling(G4double, G4double, G4double, G4double&, G4double&);
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// material dependent MSC parameters (computed at initialisation) regarding
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// Moliere's screening parameter
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G4double GetMoliereBc(G4int matindx){return (*fgMoliereBc)[matindx];}
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G4double GetMoliereXc2(G4int matindx){return (*fgMoliereXc2)[matindx];}
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private:
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// hide assignment operator and cpy ctr.
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G4GoudsmitSaundersonTable & operator=(const G4GoudsmitSaundersonTable &right);
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G4GoudsmitSaundersonTable(const G4GoudsmitSaundersonTable&);
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// load precomputed CDFs of MSC angular distributions over a 2D parameter grid
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// CDFs are stored in a variable transformed, equally probable intervall form
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// together with the corresponding rational interpolation paraneters
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void LoadMSCData();
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void LoadMSCDataII();
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// initialisation of material dependent Moliere's MSC parameters
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void InitMoliereMSCParams();
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private:
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//@{
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/** size of grids of some parameters */
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static const G4int fgNumLambdas = 76; /** number of \f$ s/\lambda_{e} $\f-values */
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static const G4int fgNumLamG1 = 21; /** number of \f$ s/\lambda_{e}G_{1} $\f-values */
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static const G4int fgNumLamG1II = 22; /** number of \f$ s/\lambda_{e}G_{1} $\f-values */
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static const G4int fgNumUvalues = 101; /** number of u-vaues */
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static const G4int fgNumScreeningParams = 160; /** number of A-vaues */
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//@}
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//@{
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/** girds of fixed parameter values */
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/** the grid \f$ s/\lambda_{e} $\f-values; size = fgNumLambdas = 76 */
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static const G4double fgLambdaValues[];
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/** the grid of \f$ s/\lambda_{e}G_{1} $\f-values; size = fgNumLamG1 = 11 */
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static const G4double fgLamG1Values[];
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static const G4double fgLamG1ValuesII[];
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/** the grid of u-values; size = fgNumUvalues = 101 */
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static const G4double fgUValues[];
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//@}
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// precomputed G1(A) function as a table -> run time interpolation to determine
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// the screening parameter value A that gives back the given first transport
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// coefficient G1
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static const G4double fgG1Values[];
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static const G4double fgScreeningParam[];
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static const G4double fgSrcAValues[];
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static const G4double fgSrcBValues[];
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//@{
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/** Precomputed equaly probable inverse CDF-s over the 3D parameter grid plus
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* precomputed parameters necessary for proper rational interpolation of the
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* inverse CDF.
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*/
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static G4double fgInverseQ2CDFs[fgNumLambdas*fgNumLamG1*fgNumUvalues];
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static G4double fgInterParamsA2[fgNumLambdas*fgNumLamG1*fgNumUvalues];
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static G4double fgInterParamsB2[fgNumLambdas*fgNumLamG1*fgNumUvalues];
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static G4double fgInverseQ2CDFsII[fgNumLambdas*fgNumLamG1II*fgNumUvalues];
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static G4double fgInterParamsA2II[fgNumLambdas*fgNumLamG1II*fgNumUvalues];
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static G4double fgInterParamsB2II[fgNumLambdas*fgNumLamG1II*fgNumUvalues];
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//@}
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//@{
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/** Precomputed \f$ b_lambda_{c} $\f and \f$ \chi_c^{2} $\f material dependent
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* Moliere parameters that can be used to compute the screening parameter,
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* the elastic scattering cross section (or \f$ \lambda_{e} $\f) under the
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* screened Rutherford cross section approximation. (These are used in
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* G4GoudsmitSaundersonMscModel if fgIsUsePWATotalXsecData is FALSE.)
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*/
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static std::vector<G4double> *fgMoliereBc;
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static std::vector<G4double> *fgMoliereXc2;
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//@}
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// flag to check if data are alredy in memory
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static G4bool fgIsInitialised;
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};
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#endif
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